With rapid development of mobile communications technologies, mobile communications systems of multiple standards have emerged, such as a Global System for Mobile Communications (Global System for Mobile communications, GSM for short), a general packet radio service (General Packet Radio Service, GPRS for short) technology, Wideband Code Division Multiple Access (Wideband Code Division Multiple Access, WCDMA for short), a CDMA-2000 network, a Time Division-Synchronous Code Division Multiple Access (Time Division-Synchronous Code Division Multiple Access, TD-SCDMA for short) network, and a Worldwide Interoperability for Microwave Access (Worldwide Interoperability for Microwave Access, WiMAX for short) network. In addition to voice communication services, usually these mobile communications systems also provide data communication services. Therefore, users can upload or download various data by using the data communication services provided by these mobile communications systems.
However, in all current mobile communications technologies, an operation is performed for a single user equipment (User Equipment, UE for short). Although another enhanced mobile communications technology is used to improve reliability and/or a throughput of data transmission of a user equipment, for example, coordinated multipoint (Coordinated Multipoint, CoMP for short) transmission is used to improve reliability of a cell-edge user equipment, or carrier aggregation (Carrier Aggregation, CA for short) is used to improve a throughput of a user equipment, once an environment of the user equipment deteriorates (for example, a signal between the user equipment and a base station is not strong), the throughput and/or reliability of data transmission of the user equipment will sharply decline.